Wall and ceiling construction



Oct. 2,1962 N. NELssoN ETAL 3,056,234

WALL AND CEILING CONSTRUCTION 2 Sheets-Sheet l Filed July 27, 1959 Oct. 2, 1962 N. NELssoN ETAL WALL AND CEILING CONSTRUCTION Filed July 27, 1959 2 Sheets-Sheet 2 3,056,234 Patented Gct. 2, 1962 3,056,234 WALL AND CEILHNG CNSTRUCTION Nels Neisson, Chicago, and Friedrich Kari Knohl, Roselle,

iii., assigner-s to United States Gypsum Company, Chicago, ih., a corporation of Illinois Filed .iuiy 27, 1959, Ser. No. 829,838 3 Claims. (Ci. Sil-319) This invention relates to a wall and ceiling construction and more particularly to a rotary-type fastener adapted for use in securing wallboard to a supporting member in a dry-wall type of construction. This application is a continuation-in-part of the application Serial No. 763,228, tiled September 25, 1958.

Heretofore, in wall constructions of this type wherein the panels are secured to the supporting members by nailing, extreme difficulty has been encountered in endeavoring to overcome the problem known as nail popping. One theory suggested for the occurrence of this condition is that in the course of driving a nail through the wallboard and into the supporting member, there `are certain stresses created within the wallboard and supporting member which exert forces on the shank of the nail, tending to cause the nail to work itself out of the board. As climatic conditions change, or as the characteristics of the wall-supporting members change, these forces of stress overcome the frictional forces existing between the nail and the wallboard and supporting member, which tend to retain the nail in its driven position and thus cause a relative movement of the nail whereby the head of the nail is spaced outwardly from the surface of the wallboard. Furthermore, there is an inherent resiliency in the wallboard and supporting member which reacts to the impact of the hammer blow an-d thus produces an immediate spring-back to the nail after the driving force of the impact has been spent.

Another shortcoming associated with the use of nails for this purpose is the susceptibility of the exposed surface of the w-allboards becoming scarred or torn by the head of the hammer, as well as the nail, and thus complicate the application of a thin layer of plaster or cement over the nail-head to conceal the same. In addition, because of the non-uniform force employed to drive the nails into position, the depth of the indeutions made in the exposed wallboard surface will require unequal amounts of the plaster or cement to be applied to conceal the nail-heads so as to produce a smooth appearing wall.

Various efforts in correcting this problem have been made, but have not met with success. These efforts have included such steps as serrating the shank of the nail; changing the size and shape of the nail-head and, in some instances, resorting to the use of a screw-type fastener. In prior efforts employing screw-type fasteners, certain of the aforementioned defects associated with nail-type fasteners were overcome; however, in place of these defects, other defects were encountered which appeared to be peculiar to screw-type fasteners. Some of these latter defects were the formation, on the exposed surface of the wallboard, of a continuous annular bulge or bead which delimited the recessed screw-head; tearing of the paper layer of gypsum core wallboard, for example, by the periphery of the screw-head while the latter is being threaded into place and thus causing burrs or fibers of paper to project above the plane of the exposed wallboard surface. In addition, when using prior screw-type fasteners for this purpose, with metallic supporting members, it was found necessary to drill a hole in the supporting member before positioning the fastener, with the result that the erection time for the wall was materially increased and oftentimes proper alignment of the screw fastener with the drilled hole in the supporting member, when the panel was in place, became a frustrating experience for the erector. Because of the aforementioned defects peculiar to prior screw fasteners, the use thereof in this type of construction was never accepted in .the building trade.

Thus, it is one of the objects of this invention to provide an improved screw-type fastener for this purpose which is not beset with the aforementioned shortcomings of a nail-type fastener or prior screw-type fastener.

It is a further object of this invention to provide an improved screw-type fastener which is possessed of superior holding power and thus requires fewer fasteners as compared to prior nail-type or Screw-type fasteners.

It is a still further object of this invention to provide a screw-type fastener which is readily capable of securing gypsum core wallboard to a metallic supporting member without the formation of an undesirable bulge in the exposed panel surface, or scarring, tearing or otherwise damaging the exposed layer of the wallboard panel when the fastener has been driven to its fully assembled relation with the panel and supporting member.

It is a still further object of this invention to provide an improved screw-type fastener which is possessed of self-drilling and self-tapping means and is capable of being used with a wide variety of supporting members.

Further and yadditional objects will appear from the description, accompanying drawings and appended claims.

In accordance with one embodiment of this invention, a wall construction is provided wherein a rotary-type fastener is utilized for securing a wallboard panel to a supporting member disposed in contacting relation with the concealed surface of the panel. The fastener includes an elongated shank section which is adapted to penetrate the panel and supporting member. The leading end of the shank section is provided with means for drilling an aperture and forming threads in said aperture in the supporting member. integrally connected to the trailing end of the shank section is a head section which consists of a trailing portion and a segment. The trailing terminal portion of the head section is provided with a recess to accommodate a tool for imparting rotary motion to the fastener. The specic design of the recess for accommodation of a tlool is not a part of this inventive concept, but may be one of a great number of contig-mations, some of which are shown in United States Patents Nos. 2,046,837 and 975,285. The configuration of the segment of the head section is such that, as the fastener is moved into its fully assembled position, the segment exerts an outward and downward ironing, or spinning, lforce on the portion of the exposed surface of the panel circumjacent the opening through which the shank section passes and thus prevents any tearing, scufiing or marring of the exposed panel surface. In addition, the configuration of the head section segment is such that the volume of the panel displaced by the head and shank sections does not exceed the volume of the voids formed in the portion of the panel delimited by, and in substantial registration with, the trailing terminal portion of the head section.

For a more complete understanding of this invention, reference should be made to the drawings, wherein:

FIGURE l is a fragmentary side elevational view partially in section, showing one form of the improved fastener in one stage of assembly with a wallboard panel and supporting member;

FIG. 2 is similar to FIG. 1, but showing the fastener in fully assembled relation with the wallboard panel and supporting member;

FIG. 3 is a fragmentary sectional View taken along line 3-3 of FIG. l;

FIG. 4 is an enlarged fragmentary side elevational view of the head section of the fastener shown in FIG. 1;

FIG. 5 is similar to FIG. 4, but showing a second form of the improved fastener;

FIG. 6 is a side elevational View of a third form of the improved fastener; and

FIGS. 7, 8 and 9 are enlarged fragmentary silhouettetype views of various size and shape head sections for the improved fastener.

Referring now to the drawings and more particularly to FiGS. l and 2, a wall construction l@ is shown which, in this instance, is a dry-wall type and includes a Wallboard panel Il, a supporting member I2, and a screw-type fastener I3 for securing said panel to the member. The panel lll, as illustrated, is of conventional construction and comprises `a cellular set calcined gypsum core I4, which has each of its opposite planar surfaces covered by a paper layer l5.

The supporting member l2 is preferably for-med of sheet metal material of approximately .G20 to 0.24 thickness, but the member i2 may also be wooden. The supporting member l2 is normally of channel shape in crosssection, with the fiat surface of one of the parallel legs 16 of the channel contacting the concealed planar surface of the panel, as seen more clearly in FIGS. l and 2. lt is to be understood, of course, that the type and shape of the supporting member may vary from that shown, without departing from the scope of this invention. If desired, the surface of the channel leg le, in contact with the panel, may be roughened, for a purpose to be described more fully hereinafter.

The fastener i3, as shown in FIGS. 1 3, includes a shank section I7 and a head section 13 integrally connected to the trailing end of the shank section. A broken line 20 is shown in FIG. l which indicates the plane of connection between the head and shank sections; the plane is taken normal to the longitudinal axis A of the fastener.

The shank section 17 has a tapered leading end 2, which is threaded and slotted as shown, for example, in Patent No. 2,871,752, so as to render such shank section self-drilling with respect to both the panel lll and supporting member i2, and self-tapping as well, with respect to the latter. The leading end 2l `of the shank section may take various forms well known in the art to accomplish this result, particularly where the supporting member is formed of a material other than sheet metal; for example, wood or plastic.

In the embodiment illustrated in FIG. l, a longitudinally extending peripheral slot 22 is formed therein which is disposed to one side yof the axis A. The remainder of shank section i7 is provided with threads 23 which are in the forrn of helical convolutions having a maximum or crest diameter considerably greater than the diameter of the shank section at the trailing end plane 2Q. rihe threads formed in the leading end 2l of the shank section i7 have progressively `decreasing crest diameters. lt is to be noted that the roots of adjacent threads 23 are preferably spaced axially a substantial distance. The advantages stemming from this thread conguration are that a greater gripping or holding action is obtained between the shank section 17 and the supporting member leg portion llo, particularly when the latter is formed of sheet metal of the thickness aforementioned. A further advantage is that there is no tendency for the shank section i7 to function as a reamer with respect to the panel core 14 while penetrating same but, instead, the core material becomes tightly packed between adjacent threads and thus strengthens the frictional grip on the shank section f7 when the fastener 13 is in fully assembled position as shown in FIG 2. It is to be understood, of course, that where the core and/ or the supporting member materials differ to a considerable extent yfrom those as heretofore described, the configuration of the threads Z3 may be changed so as to more effectively cooperate with such panel and supporting member.

The head section l, as aforementioned, is integrally connected to the trailing end of shank section i7 at plane 20 and is provided with an annular planar terminal portion 24 having a depending side portion 25 which has an axial `dimension indicated in FIG. 4 by the letter (1. The range of this dimension will be described more fully hereinafter. Coaxially disposed with respect to the axis of shank section 17 and formed in the trailing end of terminal portion 24 of the head section is a pocket or socket 29 Which is adapted to accommodate the end of a tool (i.e., `a Phillips head-type screwdriver) to effect turning of the fastener to its fully assembled position (see FIG. 2).

The segment or leading section 26 of the head section Li, which interconnects the trailing end of the shank section i7 with the leading end of terminal portion 24, may assume various configurations, as indicated in FEGS. 4, 5, 7, 8 and 9. These .configurations will rbe discussed in detail hereinafter.

The overall shape of the head section l is of utmost importance in the proper functioning of the fastener with respect to the panel il. The performance of the head section ll@ depends upon the fastener l being fully assembled, as shown in PXC'. 2, without the head section i8 tearing or scuiiing the portion of the panel layer `l5 circurnjacent a very shallow recess 27 formed in the exposed surface of the panel. In addition, the head section 18 must be of a volume no greater than can be accommodated in the voids created by crushing some of the cells of the cellular gypsum core; otherwise, a bulge or bead will be formed in the exposed panel surface which delimits the recess 27.

The diiiiculty which results by reason of the tearing or scufng of layer d'5 is that the paper bers project outwardly from the surface and thus complicate the application of a cementitious material 23 within the very shallow recess 27 and pocket 29, for the purpose of concealing the terminal portion 24 of the head section. Because of these fibers a smooth appearing panel exposed surface becomes exceedingly diiiicult to obtain. If an attempt is made to remove these fibers by sanding, the condition becomes aggravated rather than lessened.

Substantially the same difficulty results, as in the case of tearing or scutiing the -layer i5, with the formation of a bulge or bead. lt has been these two problems Which have heretofore stymied the industry in the utilization of a rotary-type fastener for this type of wall construction.

ln all forms of head sections shown in FIGS. 4, 5, and 7-8, the segment 26 includes an advancing first portion 33 and trailing second portion 32 which are formed by a nonrectilinear generatrix which revolves about the axis A of the shank section 17 as a directrix. The lower end of the generatrix is spaced from the directrix an amount equal to the radius of the shank section at the plane 20 and coincides with the juncture between the shank section ll7 and the head section l. At this juncture the segment of the head section may be slightly curved, if desired, and may extend slightly further down the shank. The lower end of the generatrix is disposed closer to the directrix than any other point on the generatrix. The other, or upper, end of the generatrix, on the other hand, coincides with the line of intersection 30 between side portion 25 and segment 26 and is spaced a greater distance from the directrix than any other point on such generatrix. Starting with the lower end of the generatrix, certain of the successive points on the generatrix are spaced from the directrix at an increasing non-uniform rate, so that the upper and lower ends of the generatrix are not connected by a straight line. Thus, the generatrix is a non-constant line. The criticality of the generatrix shape resides primarily in the angles B and C which the ends of the generatrix form, respectively, with the line of intersection 30 and a plane 3l, the latter being disposed parallel to axis A and including the lower end of the generatrix or, in other words, tangential with respect to the periphery of the shank section. These angles B and C are indicated in FIG. 4. It has been found that angle B may be within the range from 5 to 25, while angle C is within the range of 35 to 50 when the axial dimension E between line Siti and plane 29 is approximately 0.06". Angle C is less when the axial dimension E is increased (i.e., angle C is 25 and E is 0.14").

The segment 26 of head section 18, shown in FIGS. 1, 2 and 4, has a configuration formed of a pair of frustoconical units 32 and 33. The -broad base of unit 32, which is the tiatter of the two frustoconics, coincides substantially with the area delimited by side 25 of trailing terminal portion 24. The small end of unit 33 coincides substantially with the area of the .trailing end of the shank section 17. The smallend of unit 32 and the broad base or end of unit 33 are preferably interconnected by an arcuate fillet F, of a radius of approximately 0.1, as shown in FIG. 4. In FIG. 4, a preferred conguration of a head section 18 is shown when the fastener 13 is formed from wire material of about 0.10 to 0.12" diameter. In the preferred form, the angle B is about to 20; angle C is about 23 to 30; dimension d is about 0.01 to 0.02, dimension E is about 0.09 to 0.14, and the dimension G of trailing terminal portion 24 is about 0.33" to 0.36".

If desired, the llet F may be omitted, in which case a definite line 34 would be formed, such as seen in FIGS. 7-9. The relative location of fillet F, or line 34, in the surface of segment 26, will depend on the combination of angles B and C utilized.

In FIGS. 7-9 the variation in configuration of segment 26 is shown in two groups of cross-hatched areas indicated as I-I, II-II and III-III', respectively. In FIG. 7, the silhouette therein shown in full lines is taken of a head section wherein the diameter of terminal portion 24 is 0.375; the dimension d is 0.02"; and the wire or rod diameter from which the fastener is formed is 0.1875. The location of plane in FIGS. 7-9, with respect to line 30, indicated as E in FIG. 4, is a constant value of 0.06". The second crosshatched area I is shown in FIG. 7 which is added to the area I when the dimension E is increased to 0.12. The angle C', in this latter situation, is indicated by dotted line H and plane 31 lto be approximately 25.

In FIG. 8 the diameter of terminal portion 24 is 0.34; the dimension d is 0.0l5; and the wire or rod diameter is 0.111. In FIG. 9 the diameter of terminal portion 24 is 0.25; the dimension d is 0005"; and the wire or rod diameter is 0.075. In FIGS. 8 and 9, second cross-hatched areas II and III', respectively, are added to areas II and III when the plane 20 is disposed about .14" from the line of intersection 30. The angles C in these latter instances are indicated by dotted lines H and plane 31 and are approximately 25. The effect of areas I, II and III is that if the silhouette of segment 26 falls therein and such segment is formed of a pair of frustoconical units such as 32 and 33, then the difficulties afore-enumerated, previously encountered in rotary-type fasteners, are avoided. The reason for this result is that the angle B is such that the surface of segment 26 exerts an ironing, or spinning, outward and downward force on the portions 15 of layer 15 adjacent the fastener shank section 17, as the fastener 13 is being rotated into its fully assembled position, as seen in FIG. 2. The phenomenon of this action of the segment surface on layer portion 15 is that the latter is smoothly deformed to the shape shown in FIG. 2, whereby tear or rupture is avoided in the exposed layer surface and a substantial part of portion 15 becomes sandwiched between the segment surface and the panel core 14 in a manner as shown in FIG. 2.

A second reason for the aforeindicated result is that the volume of the head section 18, in combination with the portion of the shank section disposed within the panel core 14 does not exceed the volume of voids or air pockets contained Within the portion of the core delimited by, and in registration with, side 25 of the head section 18. This portion of the core 14 is indicated in FIG. 2 as that disposed between broken lines Y and Z taken parallel to axis A. By Way of example, the density of the gypsum (i utilized in forming the panel core 14 varies from about 45.5 to 52.5 pounds per cubic foot. Thus, as the fastener 13 is moved to its fully assembled position (see FIG. 2), the compacted material of the core portion is absorbed by the voids.

In the form of the head section 18a in FIG. 5, the parts thereof corresponding to like parts in the head section shown in FIG. 4 will be identified by the same numbers followed by the suffix a. Head section 18a includes a terminal portion 24a and side 25a which are similar in shape to those of head section 18. The significant difference between head sections 18 and 18a resides in the configuration of segments 26 and 26a. Segment 26a is formed by a generatrix which is a smooth curve, the center of curvature being taken from a point I, such as shown in FIG. 5. The radius of curvature R emanating from point I, and the location of point J, may vary to a considerable extent because the angles B and C, which are also included in segment surface 26a, may vary within the ranges of 5-25 and 35-50 respectively. The dimension E for the aforementioned ranges of angles B and C is assumed to be 0.06."

Considering, therefore, the various shapes of a generatrix which may be utilized in forming the: configurations of segments 26 or 26a, it may be concluded that successive points on such generatrix relative to the directrix (axis A) and commencing with the lower end of the generatrix and terminating at the upper end thereof, must increase at a non-uniform rate and the angles B and C formed by the generatrix come within the respective ranges of 5-25 and 3550 where the dimension E is approximately 0.06. It is intended. that this generalized statement defining the shape of the generatrix does not include the conguration of but a single frustum of a cone, because such a configuration will be beset with the shortcomings aforenoted in regard to prior rotary-type fasteners.

A third form of improved fastener 13b is shown in FIG. 6. The parts of fastener 13b corresponding to like parts of fastener 13 will be identified by the same number followed by the suiiix 1). Fastener 13b, in this instance, is of the same configuration as fastener 13, except that the shank section 17b is not threaded throughout its longitudinal dimension. Instead, section 17b has a portion 35' thereof, adjacent the trailing end, which is Unthreaded and thus serves as a stop so as to prevent turning of the fastener 13b beyond a predetermined point with respect to the supporting member. It is to be noted that the sum of the axial dimensions of the head section 18h and portion 35 of shank section 17h is less than the thickness of the panel 11, so that the terminal portion 2417 of the head section will be recessed with respect to the exposed surface of the panel, when the fastener is in a fully assembled position with respect to the panel and supporting member.

In applying the improved fastener 13, 13a or 13b to a panel and supporting member, it is suggested that the erector utilize a power-driven screwdriver, suitable for accommodating a Phillips head-type screw, to drive the fastener into its fully assembled position. Care should be exercised in driving the fastener, that it penetrates the panel in a direction normal to the exposed panel surface. Because of the configuration of the leading end of the shank section, the fastener should readily penetrate without any appreciable vibration. As previously mentioned, the surface of the support leg 16, in contact with the concealed surface of the panel, may be roughened slightly, thereby preventing skidding of the leading end'o-f the shank section as it commences penetrating of the support leg 16.

To assure uniform driving of all the fasteners, it is recommended that the driving tool be provided with a sensing element, such as a collar adjustably mounted adjacent the head section accommodating end of the tool. The sensing element is adapted to contact the exposed panel surface after the fastener has reached its desired fully assembled position, whereupon either a clutching mechanism or switch is triggered, causing the driving torque of the tool to cease. Sensing elements of this type are well known in the field. The advantages obtained from utilizing such an element is that it expedites erection time and, secondly, by having all the head sections recessed the same amount, the application of the concealing plaster or cement is facilitated.

Thus, it will be seen that an improved dry-wall type construction has been provided utilizing a rotary-type fastener and, because of the improved design of the fastener, no tearing or scuiiing of the exposed panel surface is occasioned during assembly of the fastener with the panel and supporting member but, instead, a spinning and ironing effect is created on the panel surface by the head section of the rotating fastener. In addition, no annular bead or bulge is formed in the exposed panel surface. Either defect complicates the treatment required to produce a wall having an exposed surface possessed of a smooth appearance. Fewer fasteners are required to effectively secure a given panel to a supporting member than in instances where other prior art devices are used, because of the improved holding ability of the improved fastener. No pre-drilling or pre-tapping of either the panel or supporting member is required when utilizing the improved fastener and, thus, the erection of such a wall is greatly facilitated.

While several embodiments of this invention are shown above, it will be understood, of course, that the invention is not to be limited thereto, since many modifications may be made, and it is contemplated, therefore, by the appended claims, to Cover any such modications as fall within the true spirit and scope of this invention.

We claim:

l. A wall and ceiling construction comprising an elongated supportin member, a wallboard panel having a cellular set calcined gypsum core and an exposed fibrous layer, and a rotary-type fastener securing said panel to one side of said supporting member, said fastener including an elongated threaded shank section provided with a tapered self-drilling and self-tapping leading end extending into said panel and supporting member in a direction substantially normal to the exposed surface of said panel, and a head section integrally connected to the trailing end of said shank section and disposed within said panel, said head section having a terminal portion, the trailing end of which is at least flush with respect to the exposed panel surface; the terminal portion of said head section `being provided with a recess to accommodate a tool for imparting rotary motion to said fastener, said recess being open only at the terminal portion of said head section; the terminal portion of said head section being of generally cylindrical configuration and having the leading end thereof connected to the trailingr end of said shank section by a segment having a configuration formed by a. nonrectilinear generatrix rotatable about the axis of said shank section as a directrix, one end of said generatrix terminating at a first plane of connection between said shank and head sections and taken normal to said directrix, said generatrix one end intersecting a second plane taken parallel to said directrix and including the point of termination of said generatrix one end with said first plane at an angle of from about 25 to 50 the second end of said generatrix intersecting a third plane of connection between the leading end of said head section terminal portion and said segment taken parallel to said first plane at an angle of from about 5 to 25; said generatr'nr second end being disposed a greater distance from said directrix than any other point on said generatrix and said generatrix one end being disposed closer to said directrix than any other point on said generatrix; the volume of said head section and the portion of said shank section disposed within said panel not exceeding the volume of the voids formed within the segment of the panel delimited by, and in substantial registration with, the terminal portion of said head section.

2. A wall and ceiling construction comprising an elongated supporting member, a wallboard panel having a cellular set calcined gypsum core and an exposed fibrous layer, and a rotary-type fastener securing said panel to one side of said supporting member; said fastener including an elongated threaded shank section provided with a tapered self-drilling and self-tapping leading end extending into said panel and supporting member in a direction substantially normal to the exposed surface of said panel, and a head section integrally connected to the trailing end of said shank section and disposed within said panel, said head section having a terminal portion of generally cylindrical configuration, the trailing end of said terminal portion being flush or slghtly recessed with respect to the exposed panel surface, said terminal portion being provided with a recess to accommodate a tool for imparting rotary motion to said fastener, said recess being open only at the terminal portion of said head section, the leading end of said terminal portion being connected to the trailing end of said shank section by a segment having a configuration formed by a generatrix rotatable about the axis of said shank section as a directrix, said generatrix having angularly disposed rectilinear end portions with the adjacent ends thereof interconnected by an arcuate fillet portion, one end portion of said generatrix terminating at the trailing end of said shank section and being disposed closer to said directrix than any other point on said generatrix, said generatrix one end portion intersecting a plane disposed parallel to said directrix at an angle from about 25 to 50, the second end portion of said generatrix terminating at the leading end of said head section terminal portion and being disposed at a greater distance from said directrix than any other point on said generatrix, said generatrix second end portion intersecting a plane taken normal to said directrix at an angle of from about 5 to 25, the distance between the opposite termini of said generatrix taken axially of said directrix being from about .06 to .14; the volume of said head section and the portion of saidshank section disposed within said panel not exceeding the volume of the voids formed in the segment of the panel delimited by, and in substantial registration with, the terminal portion of said head section.

3. The wall and ceiling construction recited in claim 2, wherein the radial distance between the termini of said generatrix is from about .08" to .14.

4. A wall and ceiling construction comprising an elongated supporting member, a wallboard panel having a cellular set calcined gypsum core and an exposed brous layer, and a rotary-type fastener securing said panel to one side of said supporting member, said fastener including an elongated threaded shank section provided with a tapered drill point extending into said panel and supporting member in a direction substantially normal to the exposed surface of said panel, and a head section integrally connected to the trailing end of said shank section and disposed within said panel, said head section having a terminal portion, the trailing end of which is at least ush with respect to the exposed panel surface; the terminal portion of said head section being provided with a recess to accommodate a tool for imparting rotary motion to said fastener, said recess being open only at the terminal portion of said head section; the terminal portion of said head section being of generally cylindrical configuration and having the leading end thereof connected to the trailing end of said shank section by a segment having a configuration formed by a nonrectilinear generatrix rotatable about the axis of said shank section as a directrix, one end of said generatrix terminating at a irst plane of connection between said shank and head sections and taken normal to said directrix, said generatrix one end intersecting a second plane taken parallel to said directrix and including the point of termination of said generatrix one end with said first plane at an angle of from about 25 to 50; the second end of said generatrix intersecting a third plane of connection between the leading end of said head section terminal portion and said segment taken parallel to said first plane at an angle of from about to 25; said generatrix second end being disposed a greater distance from said directrix than any other point on said generatrix and said generatrix one end being disposed closer to said directrix than any other point on said generatrix; the Volume of said head section and the portion of said shank section disposed within said panel not exceeding the volume of the voids formed Within the segment of the panel delimited by and in substantial registration with, the terminal portion of said head section.

5. A rotary type fastener for use in securing to a supporting member a panel having a cellular set calcined gypsum core and an exposed overlying planar layer, said fastener `comprising an elongated threaded shank having a panel and supporting member penetrating leading end, and a head section integrally connected to the trailing end of said shank, said head section and shank being concentric throughout with the fastener rotary axis; said head section being provided with a terminal portion of generally cylindrical configuration and having an axial dimension from about .005 to about .02, said terminal portion trailing end surface being provided with a rotarydriving-tool accommodating recess coaxial with the fastener rotary axis, said recess intersecting only said terminal portion trailing end surface, and the leading end of said terminal portion and the trailing end of said shank being interconnected by an uninterrupted segment, configuration of which is formed by a generatrix rotatable about lthe rotary axis of said fastener as a directrix, one end of said generatrix terminating adjacent the trailing end of said shank and being spaced closer to said directrix than any other point on said generatrix, said generatrix one end intersecting a tirst plane taken parallel to said directrix and including the terminus of said generatrix one end at an angle of from about 23 to about 50, the second end of said generatrix terminating adjacent the leading end of said terminal portion and spaced from said directrix a greater distance than any other point on said generatrix, said generatrix second end intersecting a second plane taken substantially normal to said directrix and including the terminus of said generatrix second end at an angle of from about 5 to about 25, said second plane being spaced a distance of from about .06 to about .14 from a third plane taken parallel to said second plane at the connection between said shank and head section; certain successive points on the generatrix between the termini thereof and commencing with said one end thereof being spaced from said directrix at an increasing non-uniform rate toward said generatrix second end whereby said head section segment is adapted to exert a spinning and clamping force against the exposed panel surface upon said fastener head being progressively rotatably driven into panel embedded relation in a direction normal to the exposed panel surface without injury thereto.

6. A rotary type fastener for use in securing to a supporting member a panel having a deformable inner body as for example gypsum material and an exposed overlying la er of sheet material such as papier, said fastener comprising an elongated threaded shank having a pointed leading end for penetrating a panel and supporting member, said point being coaxial with the fastener rotary axis, and a head formed at the trailing end of said shank; said head including a terminal section concentric with the fastener rotary axis and having an uninterrupted generally cylindrical surface configuration of an axial extent from about .005 to about .02, said terminal section also having an exposed end surface positioned within the confines of a transverse plane which includes the margin determined by the intersection of said end surface with said generally cylindrical surface, said head being provided with a rotary-driving-tool accommodating recess intersecting only said exposed end surface and extending therefrom axially of said fastener and terminating within said leading section, said head also including an uninterrupted leading section having an axial extent from said terminal section of from about .06 to about .14" and interconnecting with said terminal section at an angle from about 5 to about 25 with respect to a plane taken perpendicular to the fastener rotary axis and interconnesting with said shank trailing end at an angle from about 23 to about 50 with respect to a plane taken parallel to the fastener rotary axis, said leading section having an advancing first portion, the surface configuration of which flares gradually outwardly from said shank trailing end and having a maximum diameter greater than the crest diameter of the threads on said shank end, and a trailing second portion, the surface configuration of which flares outwardly from the maximum diameter of said first portion at a greater rate than said first portion and terminates at the generally cylindrical surface of said head terminal section, said Haring surfaces of the leading section being concentric with the fastener rotary axis and presenting a smooth spinning and clamping circumferential area extending from said terminal section to said shank trailing end; said shank, the penetrating point thereof, and said head being concentric with the rotary axis of said fastener whereby the flaring surfaces of said leading section of the head are adapted to exert a spinning and clamping force against the exposed surface of the panel upon said fastener being progressively rotatably driven into panel embedded relation in a direction normal to the exposed panel surface without injury thereto.

7. The fastener recited in claim 6 wherein the advancing first portion and the trailing second portion of said head leading section comprising a pair of coaxially disposed inverted frustoconical units with the larger end of the advancing first portion unit being in substantially coincident relation with the smaller end of said unit forming said trailing section.

8. The fastener recited in claim 6 wherein the trailing end of said shank is Unthreaded.

References Cited in the le of this patent UNITED STATES PATENTS 29,963 Freeman Sept. 1l, 1860 1,926,686 Newton Sept. l2, 1933 2,101,001 Balduf Nov. 30, 1937 2,479,730 Dewar Aug. 23, 1949 2,764,053 Lovisek Sept. 25, 1956 2,871,752 Stern Feb. 3, 1959 

